1. Field of the Invention
The present invention relates to a contact and transportation mechanism comprising a suction unit equipped with a floating mechanism. The suction unit is employed by an autohandler for directly pressing an IC held thereby on an IC socket in order to measure IC of an high measuring frequency.
2. Description of the Related Art
A conventional structure of a contact and transportation mechanism and that; of a suction unit will be described hereinafter with reference to FIG. 5. FIG. 5 is a cross-sectional view of an autohandler connected to an IC tester in such a way as to cover the test head thereof. Denoted at 20 in FIG. 5 is a measuring substrate provided on the upper surface of the test head, and a plate-shaped adapter 20C is mounted on the measuring substrate 20. IC sockets 21A and 21B are arranged on the adapter 20C leaving a given space therebetween.
Denoted at 90 in FIG. 5 is a substrate serving as a basis for the measuring portion of the autohandler, and a floating substrate 9 is provided on the substrate 90. The floating substrate 9 is freely movable on the substrate 90 since the former is placed on the latter by way of bearings 9B. A U-shaped casing 91 is attached to the lower surface of the central portion of the floating substrate 9 in such a manner as to project therefrom. Guide substrates 92A and 92B are attached to the lower surface of the casing 91.
Stepped holes 92C and 92D are formed in the guide substrates 92A and 92B respectively, and the stepped holes 92C and 92D are arranged on the casing 91 leaving the same space therebetween as that between the IC sockets 21A and 21B. In FIG. 5, the stepped portions of the stepped holes 92C and 92D are guided by the outline of the IC socket 21A so that the positional relationship between the measuring substrate 20 and the floating substrate 9 can be determined.
A through hole through which the mounting screw portion of a clamp lever 9A is inserted is formed at a peripheral portion of the floating substrate 9, the internal diameter of the through hole being sufficiently larger than the outer diameter of the mounting screw portion. As a result, the floating substrate 9 is fixed to the substrate 90 by the clamp lever 9A after the positional relationship therebetween is determined. In this way the autohandler is connected to the test head.
A horizontally moving substrate 10F is placed on the floating substrate 9 to be coupled thereto by way of a linear guide. A base 10G is mounted on the horizontally moving substrate 10F, and a holding block 10H is movably held by the base 10G. When a cylinder 10J is actuated, the holding block 10H moves vertically. Suction units 10A and 10B are attached to the holding block 10H leaving the same space therebetween as that between the stepped holes 92C and 92D.
Each of the function units 10A and 10B comprises a suction pad embedded therein at the lower portion thereof for retaining an IC thereon by suction. When the cylinder 10J lowers the suction units 10A and 10B from the state illustrated in FIG. 5, the presser portions 10C and 110D press the leads of the ICs on the contacts of the IC sockets 21A and 21B.
Then, the operation of the autohandler illustrated in FIG. 5 will be described hereinafter with reference to FIG. 6. FIG. 6 is a plan view of the autohandler in FIG. 5 viewed from above schematically showing the feeding mechanism thereof. Denoted at 60 in FIG. 6 is a feeding stage placed on the floating substrate 9, and 70 is an accommodating stage placed on the substrate 90. Recesses 61A and 61B for guiding the ICs in posture are formed on the feeding stage 60. Recesses 71A and 71B for guiding the ICs in posture are formed on the accommodating stage 70. The distance between the centers of the recesses 61A and 61B and that between the centers of the recesses 71A and 71B are set to be the same as that between the centers of the IC sockets 21A and 21B.
In FIG. 6, ICs are fed to the recesses 61A and 61B by an autohandler, not shown. Then the suction units 10A and 10B move onto the feeding stage 60 to retain the ICs thereon by suction. Thereafter the suction units 10A and 10B move onto the IC sockets 21A and 21B to press the ICs thereon for measurement. After the measurement, the suction units 10A and 10B release the ICs to go away leaving the same behind. The ICs left on the IC sockets 21A and 21B are transported to the recesses 71A and 71B by another autohandler.
The suction units and the contact and transportation mechanism illustrated in FIGS. 5 and 6 are suited to measuring ICs of high measuring frequency since the ICs held by the suction units are directly pressed on the IC sockets. However, coupling or transportation is difficult to the conventional contact mechanism in case of ICs comprising leads which are arranged extremely close to one another and are fragile being narrow in width such as a recent QFP type IC.
Particularly in case of an autohandler for measuring two ICs arranged in parallel as illustrated in FIG. 6, it is required to couple the autohandler to the test head while accurately conforming the interval between the centers of the cylinders to that of the two IC sockets or accurately transport the two ICs in the autohandler. The structure illustrated in FIG. 5 has a limit in improving assembling accuracy or parts accuracy, and moreover has a problem that it takes a long time for coupling.